The present invention relates to geoconversion of coal into oil, and more specifically to subsurface conversion in existing oil wells. "Geoconversion" is defined as the utilization of the natural geological forces of heat and pressure to convert prepared coal into a petroleum product, specifically oil.
It is well known that the application of sufficient heat and pressure to coal will cause conversion of the coal into oil. Most techniques using this principle have sought to create such conditions above ground where the coal is present after mining. This results in a significant expense in building apparatus to create such conditions, as well as wasting energy.
Techniques are also known for in situ subsurface conversion of non-mined coal into oil, see for example U.S. Pat. No. 4,057,293, granted to Donald E. Garrett, and U.S. Pat. No. 2,595,979, granted to E. F. Pevere et al. U.S. Pat. No. 4,140,184 granted to Ira C. Bechtold et al. discloses the injection of an aqueous slurry of a carbon containing material selected from a specified group, including limestone and oil, into a hot subterranean chamber for reaction with water in the presence of heat supplied from a hot magma.